 Mars is the world next door. The fourth planet from the sun, and quite likely the first planet on which human explorers will one day land. Spacecraft have surveyed its immense canyons and towering volcanoes. Landers have photographed pink skies and a desert filled with boulders. Like Earth, Mars has seasons that turn summers into winters, raging dust storms sometimes sweep over the planet, blocking its surface from view. While past missions to Mars have enhanced our knowledge of the planet, discoveries have led to important new questions. To answer some of these questions, NASA's Jet Propulsion Laboratory is sending a spacecraft on a journey in 1992 to map the Martian environment. Unlike Earth, Mars lost most of its atmosphere long ago. It grew cold and dry, so cold that some of its thin carbon dioxide atmosphere froze at the winter pole. How did a world formed at the same time and of the same materials as Earth become so cold, parched and relatively airless? Dr. Arden Albee of the California Institute of Technology is the project scientist representing more than 100 scientists throughout the world who work with the Mars observer data. To understand these questions about Mars and to investigate others, the Mars observer spacecraft will map the entire surface of the planet in much the same way that Earth orbiting satellites study the surface of our Earth, mapping from pole to pole. The primary goals of the mission are to understand the chemical and mineral nature of the surface. To measure the surface topography and to create a relief map of the entire planet. To study the gravity field and to search for a magnetic field. This mission will help us to understand the planet's climate now and in the past. Mars observer will give us a basic global understanding of the planet for future exploration. NASA and JPL contracted with General Electric Corporation's Astro Space Division to build the spacecraft. Weighing more than 5,000 pounds, Mars observer was specially designed for launch aboard a Titan III rocket booster built by the Martin Marietta Astronautics Group. Mars observer sits atop this 12-story high vehicle. After the Titan has placed the spacecraft into Earth orbit, a second rocket booster that transfer orbit stage from Orbital Sciences Corporation will fire to free the spacecraft from Earth's gravity. Mars observer will then be on its way to Mars. Some of the spacecraft's solar panels, its dish-shaped communications antenna and two booms carrying science instruments will be partially deployed right after launch. The spacecraft will first unfold four of its solar panels to begin drawing solar power. Then two science booms will be deployed. One carrying the magnetometer, the other supporting the gamma-ray spectrometer. That's the way we'll fly to Mars. In August 1993, after 333 days in space, the spacecraft will reach Mars and enter an elliptical orbit around the planet. The flight path will be carefully adjusted over four months until Mars observer is in a nearly circular orbit around the poles. At that time, all booms will be fully deployed. In other words, the spacecraft will open up like a flower. The spacecraft will keep its scientific payload continuously pointed at Mars. Seven science instruments will spend an entire Martian year, about 687 Earth days, exploring the planet on a global scale. Acting as a remote weather station, Mars observer will report on the planet's thin, hazy atmosphere and changing climate. Volcanoes and other landforms will be studied to determine the geological processes that have shaped the surface of Mars. A search will be conducted for evidence of a magnetic field. Scientists will want to know if water once flowed on Mars, as the Mariner and Viking missions suggested. If so, where is it now? Were conditions for life on Mars more favorable in the distant past? JPL's Advanced Multimission Control Center will be supported by NASA's Deep Space Network. The mission will be the first to provide a database at JPL that scientists will be able to access from their home institutions. Specially designed workstations will connect them to the data center at JPL. As part of an international effort, Russian instrument packages will be landed on the Martian surface in the mid-1990s. Mars Observer carries a radio system supplied by the French space agency to support these missions. This radio system will allow the spacecraft to receive and relay data from the instrument packages on the surface. As the data is processed, the Mars Observer mission will help us understand the evolution of our planetary neighbors and provide a legacy for human exploration.